EXPERIMENTS WITH POTASH-BORDEAUX. A third fungicide was used the present season, in which the lime of the common Bordeaux was replaced by caustic potash (potassium hydrate). Copper sulphate, neutralized with this alkali, has been styled potash-bordeaux. It was prepared according to the following formula: Copper sulphate... 5 pounds. 3 pounds. 50 gallons. The potash here considered is obtained in bulk, is more or less impure and costs a few cents a pound by the barrel or drum. To bring the hard lumps into solution they may be placed in a kettle of bot water, where they soon become dissolved. Twenty pounds of the caustic potash readily dissolve in five gallons of water and may be kept as a stock solution until desired, in large bottles or a demijohn. A purer form of potash may be obtained in cans, in which case the lid of the can is removed and the can inverted in the kettle, where, with hot water, it is to be brought into solution and stored for use as before stated. The formula given above will vary somewhat, and when the commercially-pure potash put up in cans is employed it will be well to follow the directions suggested for soda-bordeaux. The red litmus paper will aid in detecting the presence of an excess of the potash. If the test paper turns blue more copper sulphate should be added, but if it remains unchanged potash needs to be added until the test paper shows the slightest tinge of blue, when no more of the alkali should be added. Like the soda-bordeaux, the potash-bordeaux, if alkaline, changes in color after a time and the precipitate then settles more quickly than before. This change does not take place so soon, however, as in the soda-bordeaux, and if care is exercised not to add an excess of the potash no difficulty need be experienced on this account. The potash-bordeaux is eventually washed off the foliage and becomes a part of the soil, and, being a desirable plant-food, it thus becomes a valuable fertilizer after having served as one of the constituents of a fungicide. Potash-Bordeaux with Potatoes. In 1896 potash-bordeaux was applied, upon the same dates as the other two fungicides employed, to the third belts of all four plots of Series II. and to the third belts of the plots devoted to potatoes in Series III., IV. and V. A portion of the potatoes in Series VI. were sprayed six times with the same mixture. Since the potato vines throughout the experiment area were almost wholly uninfested by leaf blight, no opportunity was afforded for testing the efficiency of the fungicide under consideration. Potash-Bordeaux with Beans. Two belts of the first crop of beans were sprayed in 1896 with potash-bordeaux, the number and dates of application of this fungicide being the same as those of Bordeaux and soda-bordeaux. In the potash-bordeauxed belt of Series V. the percentage of spotted pods at harvest time was lower than in either of the other two sprayed belts adjoining; but in the plot of Series IV., the potash-bordeauxed belt, although much less infested than the check, was somewhat more so than the adjoining bordeauxed belt or the soda-bordeauxed belt. In the second crop of wax beans the potash-bordeauxed belt contained a somewhat smaller proportion of spotted pods than did the bordeauxed belt and only about one-sixth as many as did the check. One belt of lima beans was sprayed with potash-bordeaux, but as already stated, this crop was uninjured by disease, and hence no result followed from the application of fungicides. Potash-Bordeaux with Tomatoes. The third belt of tomatoes was sprayed with potash-bordeaux in 1896, with results decidedly favorable to this fungicide. Up to the time when they were destroyed by frost the plants in the belt so treated were not sufficiently infested by tomato leaf blight to interfere with the normal development of the fruits. On the other hand, the plants in the adjoining check were injured to such an extent by disease that a large proportion of the fruits were decidedly inferior, both in size and in quality. The percentage of leaf blight in the potashbordeauxed belt seemed to be fully as low as in the bordeauxed belt, while the percentage of fruit rot was somewhat higher. Potash-Bordeaux with Peppers. About as many spotted fruits developed the present season, in the belt of peppers sprayed with potash-bordeaux, as in the check belt. Like negative results were obtained in this crop from the use of Bordeaux. Potash-Bordeaux with Egg-plants. A liberal use of potash-bordeaux (fourteen applications) failed in 1896, as did Bordeaux and soda-bordeaux, to check the development of the fruit rot of egg-plants. Potash-Bordeaux with Cucumbers. Until destroyed by insects, the cucumber vines, sprayed with potashbordeaux, were noticeably less infested by leaf blight than were those in the check belts. In the plot in which the fruits were left upon the ground to ripen, the proportion infested at harvest time by rot was only about one-fourth as great as in the check. As a preventive of cucumber leaf blight and fruit rot, potash-bordeaux gave evidence of being fully as efficient as Bordeaux. Potash-Bordeaux with Celery. None of the blights common to celery appeared in the crop upon the experiment area the present season, and therefore no results followed from the application of fungicides. Potash-Bordeaux with Beets. The twelve applications of potash-bordeaux to one plot of beets in 1896, resulted even more favorably than did a like number of applications of Bordeaux. The weight of roots produced in the potashbordeauxed belt was greater than that produced in an adjoining and somewhat more fertile check, by 47.5 per cent. There was an increase in the weight of the foliage of sprayed beets over that of those in the above check, of 78.5 per cent. Potash-Bordeaux with Sweet Potatoes. There was noticeably less mildew upon the sweet potato vines sprayed with potash-bordeaux than upon the adjoining unsprayed ones. Potash-Bordeaux with Cosmos. The cosmos plants sprayed with potash-bordeaux were to all appearances as thoroughly infested by the stem blight as were the untreated plants. Potash-Bordeaux with Sunflowers. A portion of a row of sunflowers was sprayed seven times the present season with potash-bordeaux. From a careful comparison made near the end of the season, it was estimated that there was only about one-eighth as many rust pustules upon the leaves of the sprayed plants as upon those of the checks. The results obtained from the use of potash-bordeaux were slightly better than those which followed from the use of Bordeaux. Like Bordeaux, potash-bordeaux had no appreciable effect upon the sunflower stem blight. Potash-Bordeaux with Hollyhocks. As a preventive of hollyhock leaf blight, potash-bordeaux proved as effective as did Bordeaux. The leaves of adjacent unsprayed hollyhocks were considerably blighted. Potash-Bordeaux with Cercis. The four cercis trees sprayed with potash-bordeaux remained uninfested by leaf blight throughout the season. The unsprayed were slightly blighted. Potash-Bordeaux with Peonies and Gladiolus. Since the unsprayed pæɔnies and gladiolus were not attacked by disease the present season, no results were obtained from the use of potash-bordeaux. EXPERIMENTS WITH AMMONIA-BORDEAUX. A fourth fungicide, termed ammonia-bordeaux, was given a comparative trial with the three already considered. It was made up in the following proportions: Copper sulphate......... Ammonia....... Water.. 5 pounds. 5 pints. 50 gallons. The formula for ammonia-bordeaux, as above stated, differs from that for the fungicide known as Eau Celeste, in that the former calls for one-third less ammonia than the latter.* In the ammonia-bordeaux it was desired to add only sufficient ammonia to produce an alkaline reaction. In preparing a given quantity of ammonia-bordeaux, the alkali should be diluted as recommended in case of lime, soda and potash. For example, if ten gallons of the mixture are to be prepared, the one pint of ammonia should be diluted to five gallons and thoroughly stirred into the copper sulphate solution. As prepared at first, the mixture contained ammonia in excess of the quantity called for in the above formula, and as a consequence the foliage was greatly injured by burning. Later, the proportion of ammonia used was barely sufficient to produce an alkaline reaction, and the injury from burning was greatly diminished, but the foliage was still noticeably injured. The number of crops treated with ammonia-bordeaux was not so great as in case of the other three fungicides, but a sufficient number were treated, however, to give the mixture a fair trial. On account of its caustic action upon the foliage, the use of ammonia-bordeaux can scarcely be recommended, although as a fungicide it was perhaps equal to any of the other three employed. Ammonia-Bordeaux with Beets. The ammonia-bordeaux was employed the present season as a preventive of beet leaf blight. In all, twelve applications of the mixture were made. The untreated beet plots were badly blighted, but the plot sprayed with the ammonia-bordeaux was comparatively uninfested. The fungicide, as used for the first three or four applications, was found to contain a larger percentage of ammonia than was necessary, the result being that the beet foliage so treated was severely burned. After reducing the proportion of the alkali, the degree of burning was materially lessened, but the objectionable feature was not wholly removed. As a result the yield of roots from that portion of the field so treated was but little more than half as great as in adjacent plots treated with other fungicides. Compared with its check *Instead of Eau Celeste, a less caustic mixture, known as Modified Eau Celeste, is sometimes used, in which the carbonate of soda in addition to ammonia is employed. |